Various devices have been presented in the past to interface between a light bulb and its lampholder for the purpose of extending the rated life of the incandescent bulb.
One such currently available device comprises a relatively large (21/4" long.times.11/4" diameter) insulator adaptor threadingly mounted into the lampholder and into which the lamp bulb is threaded. A rectifying diode circuit is provided within the casing or housing of this adaptor, but because of its large and cumbersome size this type adaptor has only limited application. Another type of bulb saver or extender is formed as a circular disc of a substantially 1/8" thickness which is freely dropped or inserted into the lampholder socket; the light bulb being threaded into the lampholder socket over the adaptor. The device employs a standard diode having lead conductors in contact with the center contacts of the light bulb and lampholder socket. Because of its relative heavy thickness, the live or energized shell of the light bulb base is exposed beyond the upper end of the lamp socket endangering the user to shock hazards.
Still, another bulb extender device employs a silicon rectifier mounted in the center of an approximately 1" diameter insulator carrying soldered faces for engagement with the central contacts of the socket and light bulb. The device is freely inserted into the lampholder socket and the light bulb is threaded thereinto in normal manner. Because of the central positioning of the diode chip, threading the bulb into the socket often breaks the diode and the device fails.
In general, such previous known devices have been subject to criticism and non-acceptance because of cumbersome design and limited application, or because their thickness causes the light bulb to extend out of the lampholder sufficiently to expose the bulb's live metal case to the user. Devices which are inserted into the lampholder socket also expose the user to shock hazards when installing the device, particularly if the lampholder is energized. In still other instances, criticism has been encountered because of the inability of the devices to withstand relatively high operating temperatures (in the nature of 200.degree. centigrade), encountered in some applications.